Bottom Line:
An analysis of 2001 and 2002 West Nile virus (WNV) surveillance data shows that counties that report WNV-infected dead birds early in the transmission season are more likely to report subsequent WNV disease cases in humans than are counties that do not report early WNV-infected dead birds.

ABSTRACTAn analysis of 2001 and 2002 West Nile virus (WNV) surveillance data shows that counties that report WNV-infected dead birds early in the transmission season are more likely to report subsequent WNV disease cases in humans than are counties that do not report early WNV-infected dead birds.

Figure 1: Counties reporting avian deaths and human illness caused by West Nile virus (WNV), January 1–December 31, 2001. Counties reporting human illness are outlined in red. The color within the county indicates the date when the first avian death from WNV was reported in that county. Counties that report dead birds early in the year are more likely to report subsequent disease cases in humans.

Mentions:
Of 93 counties that reported at least one WNV-infected bird before August 5, 28 (30%) subsequently reported a human WNV disease case in 2001 compared to 11 (4.7%) of 235 counties that did not report an infected bird (RR 6.43, 95% confidence interval [CI] 3.34 to 12.38). In other words, in 2001, counties that reported a WNV-infected dead bird before August 5 were more than six times more likely than other counties to report a human WNV disease case (Figure 1).

Figure 1: Counties reporting avian deaths and human illness caused by West Nile virus (WNV), January 1–December 31, 2001. Counties reporting human illness are outlined in red. The color within the county indicates the date when the first avian death from WNV was reported in that county. Counties that report dead birds early in the year are more likely to report subsequent disease cases in humans.

Mentions:
Of 93 counties that reported at least one WNV-infected bird before August 5, 28 (30%) subsequently reported a human WNV disease case in 2001 compared to 11 (4.7%) of 235 counties that did not report an infected bird (RR 6.43, 95% confidence interval [CI] 3.34 to 12.38). In other words, in 2001, counties that reported a WNV-infected dead bird before August 5 were more than six times more likely than other counties to report a human WNV disease case (Figure 1).

Bottom Line:
An analysis of 2001 and 2002 West Nile virus (WNV) surveillance data shows that counties that report WNV-infected dead birds early in the transmission season are more likely to report subsequent WNV disease cases in humans than are counties that do not report early WNV-infected dead birds.

ABSTRACTAn analysis of 2001 and 2002 West Nile virus (WNV) surveillance data shows that counties that report WNV-infected dead birds early in the transmission season are more likely to report subsequent WNV disease cases in humans than are counties that do not report early WNV-infected dead birds.